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  <div><b id="oldnode">JavaScript</b>是一个很常用的技术，为网页添加动态效果。</div>
  <a href="javascript:replaceMessage()"> 将加粗改为斜体</a>

  <script type="text/javascript">
    function replaceMessage() {
      var old = document.getElementById("oldnode");
      var newnode = document.createElement("i");
      //替换其中的html代码
      newnode.innerHTML = oldnode.innerHTML
      old.parentNode.replaceChild(newnode, old);

    }
  </script>

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